1. Open applications > AppleScript > Script Editor
2. Enter this text:
3. Save it as an application (File > Save as and set the file format pop-up to application)
And that's it! Simple as that. You can now use your color picker any time you want.
To add something extra to your colour picker, download the HexColorPicker. This adds another tab to the color picker bar which tells you the exact number/letter identification of the colour you have chosen. Very handy for when working on the web. Read the help file that comes with this download to tell you where to place the bundle in your directory (very simple).
One more something extra. Your colour picker allows you to create your own palettes and save for later use. This tutorial talks you through the very simple steps.